1. Field of the Invention
This invention pertains generally to the field of heat sealable bags adapted for packaging meats and similar products, and particularly those which are adapted to be evacuated to draw the bag tightly around the meat product before the bag is sealed.
2. Description of the Prior Art
Cuts of meat are often packaged in plastic bags which are evacuated and heat sealed before delivery to the customer. Such packaging is particularly common with so called primal cuts of meat such as roasts and rib sections. Typically, such cuts of meats have substantial portions of bone remaining in them, and often the bones will protrude away from the meat itself. This can present a problem when evacuating the meat package, since sharp bones can puncture the walls of the bag.
In conventional vacuum packaged meats, a puncture of the bag wall will release the vacuum packaging on the meat and allow air to migrate around the bag, resulting in deterioration of the meat from contact with the air and considerable leakage of the fluids contained in the bag with the meat. This problem has been minimized by utilizing a post sealing treatment which involves heating the sealed package to cause heat sealable inner surfaces of the bag walls to seal together where these walls have been drawn together during the evacuation process. A bag sealed in this manner is mechanically held tight to the meat and will not generally separate from the meat if a portion of the bag is punctured. However, there will be drainage of fluid from the meat package and localized introduction of air into the package which can damage the meat.
Various types of boneguard inserts have been used with packaging of this nature. A conventional boneguard is a wax impregnated cloth or plastic insert which is hand placed over the exposed bone before the meat is inserted in the package. These inserts do not seal to the inner surface of the outer bag layers. Additional boneguard structures include separate layers of plastic which are sealed into the bag to cover those areas which will be exposed to the protruding bones. These structures have suffered from various limitations, including relative high cost of labor and materials involved in placing the inserts properly into the bag, and locating the meat so that the bone abuts the insert. In addition, the inserts often have not adequately protected the bag from the effects of protruding bones, so that punctures are still possible.